P2RX1 and leukemia: We next established an MLL-AF9-induced murine AML model as previously described [34], and found that P2X1 deletion led to a notable delay in leukemia development in recipient mice receiving MLL-AF9-overexpressing P2x1-null Lin- BM cells as revealed by decreased YFP+ leukemic cell frequencies in the peripheral blood (4.3% vs. 21.4%, Fig. 1E, F and S1E, F), extended overall survival (91 vs. 62 days, Fig. 1G) and reduced leukemic cell infiltration in the spleens and livers of transplant mice (Fig. 1H, I and S1G).